Imágenes de páginas
PDF

cities of London and Westminster, or within three miles thereof, or within any other city, borough, or market-town, or one mile thereof, or within two miles of the king's palaces or magazines, or half a mile of any parish church, on pain of forfeiture, and two shillings per pound, except in licensed mills, or to the amount of three hundred pounds for the use of collieries, within two hundred yards of them.

GUNTER (edmund), an English mathematician of the seventeenth century, was descended from an ancient and respectable family in Brecknockshire, South Wales, and was born in the county of Herefordshire in the year 1580. He received his classical education on the royal foundation at Westminster School, whence he was elected at about eighteen years of age to Christ Church College, in Oxford. He was admitted to the degree of B.A. in 1603, and to that of M.A. in 1606; after which he entered into orders, and proceeded batchelor of divinity in the year 1615. His genius had early led him to the pursuit of mathematical studies; and at the time when he took his degree of M. A. he bad merited the title of an inventor by his new projection of the sector, of which he then wrote a description in Latin, ^and permitted his friends to transcribe it, though the English account of his invention was not published till several years afterwards. In the year 1618 he had iuver.ted a small portable quadrant, for the more easy finding the hour and azimuth, and more useful astronomical purposes. The reputation which he had now acquired in the mathematical world occasioned his introduction to the acquaintance of some of the most able mathematicians of his time, by whose recommendation and interest he was elected professor of astronomy at Gresham College, London, in the year l<il9. In this situation he. soon distinguished himself by his lectures and his writings, which contributed greatly to the improvement of science, and reflected credit to the choice that had been made of him to that professorship. His first publication after his election appeared in 1620, and was entitled, " Canon Triangnlorum, sive Tabulsr Sinuum artificialium ad radium 10.0000000, ct ad Scrupnla prima Quadrantis,'' 8vo. This treatise was accompanied with the first 1,000 of Brigg's logarithms of common numbers. In the second edition of it, which was published in English in 1624, under the title of " Canon Triangnlorum, or Table of artificial Signs and Tangents to a radius of 10.0000000

Parts to each Minute of the Quadrant," 4to., the logarithms were continued from 1,000 to 10,000, and rule was given at the end for augmenting them to 100,000. These tables were the first of the kind which had been given to the world, and, if the author had published nothing else, would have preserved his memory to the latest posterity, by the admirable aid which they afforded to students in astronomy; for they greatly facilitated the practical parts of that science, by furnishing a method of solving spherical triangles without the aid of secants or versed sines; the same thing being effected by addition and subtraction only, which in the use of the former tables of right sines and tangents required multiplication and division. Due praise was bestowed upon him by many of the most eminent mathematicians among his contemporaries for the service which he rendered to science by this most excellent work; and his right to the. improvement of logarithms, by their application to spherical triangles, was satisfactorily established by Mr. Edmund Wingate, Mr. Robert Burton, and Mr. Henry Bond, Sen.

In the year 1623 Mr. Gunter made his important discovery, that the variation of the magnetic needle varies. To this discovery he was led in the course of lectures he made on the variation at Deptford, by which he found that the declination of the needle had changed almost five degrees in the space of forty-two years. The truth of this discovery was afterwards confirmed and established by Mr. Gcllibrand, his successor at Gresham College. Soon after this he invented his famous "rule of proportion," which is an easy and excellent method of ■ combining arithmetic and geometry, adapted to the understanding of persons of the most ordinary capacities. It consists in applying the logarithms of numbers and of sines and tangents to straight lines drawn on a scale or rule, by which, proportions in common numbers and trigonometry, may be resolved by the mere application of a pair of compasses: a method founded on this property, that the logarithms of the terms of equal ratios are oquidiHVrcnt. This was called Gunter's proportion and Gunter's line; and the instrument in the form of a two foot scale is now in common use for navigation and other purposes, and is commonly called the Gunter. In the year 1624, this invention was carried into France by Mr. Wingate, who not only communicated it to most of the principal mathematicians then at Paris, but also, at their request, published an account of it in the French language. Mr. Gunter likewise greatly improved the sector, and other instruments for the same uses, the description of all which he published in 1624, in a treatise entitled " The Cross Staff, in three Books," &c. 4to. In the same year he published, by King James', order, a small tract, entitled, "The Description and Use of his Majestie's Dials in Whitehall Garden," 4to. Mr. Gunter had been employed by the direction of King Charles in drawing the lines on these dials, and at his desire wrote this description, to which we refer those readers who wish to see a particular account of the construction and uses of those dials, which are no longer in existence. Our author was the first who used the word co-sine for the sine of the complement of an arc. He also introduced the use of arithmetical complements into the logaHthmical arithmetic; and it has been said, that he first started the idea of the logarithmic curve, which was so called because the segments of its axis are the logarithms of the corresponding ordinates. To him likewise the mathematical world is indebted for many other inventions and improvements, most of which were the subjects of his,lectures at Gresham College, and afterwards disposed into ureatises,which were printed in his works. From the genius and abilities which he had displayed in his works already noticed, the highest expectations were formed of his future services in the cause of useful science; but they were unhappily disappointed by his death, in 16<J6, when he was only in the forty fifth year of his age. His name, however, will be transmitted with honour to posterity, as that of the parent of instrumental arithmetic. His works have been collected, and various editions of them have been published. The fifth is by William Leyhourn, in 16T3, Ho., containing the description and use of the sector, cross-staff, bow, quadrant, and other instruments ; with several pieces added by Samuel Foster, Henry Bond, and William Leybourn.

Gunter's chain, the chain in common use for measuring land, according to true or statute measure; so called from Mr. Gunter, its reputed inventor. The length of the chain is 66 feet, or 2 2 yards, or 4 poles, of ij yards each; and it is divided into 100 links, of 7.94 inches each. This chain is the most convenient of any tiling for measuring land, because the contents thence computed are so easily turned into acres. The reason

of which is, that an acre of land is just equal to 10 square chains, or 10 chains in length and one in breadth, or equal to 100,000 square links. Hence, the dimensions being taken in chains, and multiplied together, it gives the content in square chains, which therefore being divided by 10, or a figure cut off for decimals, brings the content to acres; after which the decimals are reduced to roods and perches, by multiplying by 4 and 40. But the better way is to set the dimensions down in links, as integers, considering each chain as 100 links, .then, having multiplied the dimensions together, producing square links, divide these by 100,000 that is, cut off five places for decimals, the rest are acres, and the decimals are reduced to roods and perches as before. Suppose a field to be measured be 887 links in length, and 760 in breadth, to find its area we say 887

750 44350 6209

6.65250 4

2.61000 40

24.4

The contents are 6 A. 2 R. 24 P.

Gunter's line, a logarithmic line, usually graduated upon scales, sectors, &c. It is also called the line of lines, and line of numbers; being only the logarithms graduated upon a ruler, which therefore serves to solve problems instrumcntally in the same manner as logarithms do arithmetically. It is usually divided into an hundred parts, every tenth thereof is numbered, beginning with 1, and ending with 10; so that if the first great division, marked 1, stand for one tenth of any integer, the next division, marked 2, will stand for two-tenths; 3, threetenths, and so on; and the intermediate divisions will, in like manner, represent 100th parts of the same integer. If each of the great divisions represent 10 integers, then will the lesser divisions stand for integers; and if the great divisions be supposed each 100, the subdivisions will be each 10.

Gunter's line, use of. l. " To find the product of two numbers." From 1 extend the compasses to the multiplier; and the same extent, applied the same way from the multiplicand, will reach to the product. Thus, if the product of 4 and 8 be required, extend the compasses from 1 to 4, and that extent laid from 8 the same way, will reach to '32, their product. 2. "To divide one number by another." The extent from the divisor to unity will reach from the dividend to the quotient: thus to divide 36 by 4, extend the compasses from 4 to 1, and the same extent will reach from 36 to 9, the quotient sought. 3. "To three given numbers, to find a fourth proportional." Suppose the numbers 6, 8, 9; extend the compasses from 6 to 8, and this extent, laid from 9 the same way, will reach to 12, the fourth proportional required. 4. " To find - a mean proportional between any two given numbers." Suppose. 8 and 32: extend the compasses from 8 in the left-hand part of the line to 32 in the right; then bisecting this distance, its half will reach from 8 forward, or from 32 backward, to 16, the mean proportional sought. 5. " To extract the square root of any number." Suppose 25: bisect the distance between one on the scale and the point representing 25; then the half of this distance, set off from 1, will give the point representing the root 5. In the same manner the cube root, or that of any higher power, may be found by dividing the distance on the line, between 1 and the . given number, into as many equal parts as the index of the power expresses; then one of those parts, set from 1, will find the point representing the root required.

Glnter'j quadrant, one made of wood, brass, &c containinga kind of stenographic projection of the sphere, on the plane of the equinoctial; the eye being supposed placed in one of the poles. Besides the use of this quadrant in finding heights and distances, it serves also to find the hour of the day, the sun's azimuth, and other problems of the globe.

Gunter's scale, usually called by seamen the Gunter, is a large plain scale, having various lines upon it, of great use in working the cases or questions in navigation. This scale is usually two feet long, and about an inch and a half broad, with various lines upon it, both natural and logarithmic, relating to trigonometry, navigation, &c. On the one side are the natural lines, and on the other the artificial or logarithmic ones. The former side is first divided into inches and tenths, and numbered from one to twenty-four inches, running the whole length near one edge. One half the length of this side consists of two plain diagonal scales, for taking off dimensions to three places of figures. On the other half or foot of this side, are contained various lines re

[graphic]

latin* to trigonometry, in the natural numbers, and marked thus, Ariz.

Rumb, the rumbs or points of the compass;

Chord, the line of chords;

Sine, the line of sines;

Tang, the tangents;

S. T. the semi-tangents, and at the other end of this half are,

Leag. leagues, or equal parts;

Rumb, another line of rumbs;

M. L. miles of longitude;

Chor. another line of chords.

Also in the middle of this foot are L, and P, two other lines of equal parts: and all these lines on this side of the scale serve for drawing or laying down the figures to the cases in trigonometry and navigation. On the other side of the scale, are the following artificial or logarithmic lines, which serve for working or resolving those cases; viz.

S. R. the sine rumbs;

T. K. the tangent rumbs;

Numb, line of numbers,

Sine, sines;

V. S. the versed sines ,

Tang, the tangents;

Men. Meridional parts;

E. P. Equal parts.

GUN-WALE, or Gunnel, is the uppermost wal; of a ship, or that piece of timber which reaches on either side from the quarter-deck to the forecastle, being the uppermost bend which finishes the upper works of the hull, in that part in which are put the stanchions which support the wastetrees.

GUSSET, in heraldry, is formed by it line drawn from the dexter or sinister chief points, and falling down perpendicularly to the extreme base.

GUST, in sea-language, a sudden and violent squall of wind, bursting from the hills upon the sea, so as to endanger the shipping near the shore. These are peculiar to some coasts, as those of South Barbary and Guinea.

GUSTAVIA, in botany, so named in memory of Gustavus III, King of Sweden: a genus of the Monadelphia Polyandria class and order. Natural order of Myrti, Jussieu. Essential character: calyx none; petals several; berry many-celled; seeds appendicled. There is but one species, viz. G. augusta, which is a tree from twenty to thirty feet in height. It is a native of Surinam and Cayenne.

GUTTA Serena, a disease in which the pa

tient, without any apparent fault in the eye, u entirely deprived of sight.

Guttje, in architecture, are ornaments in the form of little cones, nsed in the plafond of the Doric cemiche, or on the architrave underneath the triglyphs, representing a sort of drops or bells. They are usually six in number.

GUTTERS, in architecture, a kind of canals in the roofs of houses, serving to receive and carry off the rain.

GUTTURAL, a term applied to letters or sounds pronounced or formed as it were in the throat, re. ]/nr\x, which, for memory's sake, are termed ahaehah.

GUTTY, in heraldry, a term used when any thing is charged or sprinkled with drops. In blazoning, the colour of the drops is to be named, as gutty of sable, of gules, Sec.

GUY, in a ship, is any rope used for keeping off things from bearing or falling against the ship's sides when they are hoisting in.

That rope, which at one end is made fast to the fore-mast, and seized to a single block at the pendant of the garnet, is called the guy of the garnet.

GYBING, the art of shifting any boomsail from one side of the vessel to another. By a boom-sail is meant any sail, the bottom of which is extended by a boom, (see Boom) the fore-end of which is hooked to its respective mast, so as to swing occasionally on either side of the vessel, describing an arch of which the mast is the centre. As the wind changes, it becomes necessary to change the position of the boom, together with its sail, which is accordingly shifted to the other side of the vessel, as a door turns upon its hinges.

GYMNANTHES, in botany, a genus of the Monoecia Monadelphia class and order. Essential character: male ament naked ;perianth and corolla none; stamina pedicels three-parted or three-forked, anther bearing; female ament or germ pedicelled; corolla none, style trifid; capsule tricoccous, three-celled. There are two species, natives of the West Indies.

GYMNASTICS. This, word, derived from the Greek, comprehends all those athletic exercises by which the ancients rendered the body pliant and healthy, and enabled the muscles to do their offices with treble effect. The variety of methods contrived for this purpose was very numerous, and the ardour with which they were pursued at every opportunity, contributed to

banish all dread of personal danger, and prepared the youth of each nation for the military life.

Persons were appointed to teach the various sports, and the gymnasium was a public receptacle for their performance; the exercises amounted to nearly sixty descriptions, and the parties concerned in them originally appeared in drawers, but afterwards totally naked, in order to give full scope to their limbs. The gymnasium was under the superintendence of a master, styled gymnasiarch, who had two assistants, the xystarch and the gymnastis. The master was selected from the higher classes of the people, as his office was of considerable importance, and his deputies presided over the inferior persons employed in teaching; the former directing the wrestlers, and the latter the progress of the other exercises, that the youths might neither suffer through accident or too violent exertion.

It has been asserted that the whole system of education amongst the Greeks, was comprehended in two essential points, gymnastics and music; dancing, under several divisions, invariably accompanied their music in warlike, festive, and bacchanalian movements, to which they added, at proper * times, tumbling, numerous modes of playing with the ball, leaping, foot-races, pitching the discus, throwing the javelin, wrestling, boxing, &c. Tumbling was entitled cubistics; the amusements of the ball they comprehended under the term spheristics; the exercises of leaping, foot-racing, the dig. ■ cus, the javelin, and wrestling, they included in the word palestrics.

The moralists and medical men of antiquity, highly approved of those sports which were calculated to bring health, strength, and grace in their train; but were energetic and vehement in their censures of the athletes, who wrestled and boxed with angry violence, and afterwards indulged in vicious excesses.

Leaping a considerable distance with ease, was one of the innocent and useful acquirements of the Grecian youth, which they soon attained, but which they appear to have . despised.as incapable of difficulty ;therefore, to render the art laborious, and increase their weight, they adopted the practice of bearing lead on their heads and shoulders, fastening it to their feet, and holding it in their hands. A youth, thus loaded, and almost pinioned to the earth by attraction, who sprung a greater distance than his competitors under the same circumstances, was

hailed with loud plaudits, proportioned to the surprise excited by his uncommon strength of muscles.

The pedestrian races admitted of more ardent endeavours than leaping; not a moment could be lost or granted for relaxation; the shouts of the teachers, and of the spectators, were incentives for exertion, and, divested of clothing, the efforts of the least successful were wonderful. Homer illustrates this part of the subject in his inimitable " Iliad."

"Rang'd in a line the ready racers stand; Pelidcs points the barrier with his hand; All start at once; Oileus led the race; The next, Ulysses, measuring pace with

pace; Behind him, diligently close, he sped, As closely following as the running thread The spindle follows, and displays the

charms Of the fair spinster's breast, and moving

arms: Graceful in motion thus, his foe he plies, And treads each footstep ere tUo dust

can rise: His glowing breath upon his shoulders

plays; The admiring Greeks loud acclamations

raise; To him they give their wishes, hearts,

and eyes, And send their souls before him as he ~ flies."

Iliad, book xxiii. 885, 89.3.

Rapidity of motion might be useful to the ancients in many particulars, though less so than to the uncivilized nations generally termed savage; the inhabitants of the latter seem indeed compelled to acquire swiftness in running, as the pursuit of wild animals is absolutely necessary to maintain their existence; and some of the native chiefs of India and its dependencies retain persons to convey dispatches from station to station by pedestrian exertion.

Throwing the dart or spear, was of decided importance in ancient warfare, and the skill of their soldiers was probably very great. In this instance, however, it may be doubted, whether all the advantages of their gymnasiums enabled them to excel sonic of the-tribes of Hottentots, exclusive of savages in a superior state of civilization; the debased people alluded to, possess wonderful ability in throwing and arresting the progress of spears; the writer of the present article had an opportunity of knowing,

from a witness of the scene, that a Hottentot frequently caught a heavy pole hurled at him by a strong man, ere it had power to injure him.

Throwing the discus, now known by the name of the quoit, required equal strength and skill; the shape of the discus was nearly oval, about a foot in length, and three or four inches thick in the centre, whence it tapered on each side to the extremity, in the manner of a lens, and a hole was perforated in the middle. Statues of persons employed at this game exhibit them with the discus "rested on the four fingers, which were closed, with their ends pointing upward on the inside of it; the thumb was extended horizontally along the outside."

Salzmann says, the thrower obtained the necessary impulse by swinging the arm, and at the proper moment he gave the discus a rotatory motion, and sent it through the air to the mark. Kcnnet asserts, in describing the Roman Circensian shows, that they obtained their quinquertium, or the five exercises of running, wrestling, leaping, throwing, and boxing, from the Grecian games, and adds, that the discus or quoit of the former people, "was made of stone, iron, or copper, five or six fingers broad, and more than a foot long, inclining to an oval five; they sent this to a vast distance, by the help of a leathern thong tied round the person's hand that threw." The latter particular has been disputed, and the position is maintained by observing, that had a thong been used, it was unnecessary for the discobuli to rub their hands on the earth, to prevent the discus from slipping; besides, the strap would have interrupted the rotatory whirl thought indispensable for its steady course.

If we may depend upon Homer, the weight of the discus was an object of some importance:

"Then hurl'd the hero, thund'ring on the

ground A mass of iron, (an enormous round) Whose weight and size the circling Greeks

admire, Rude from the furnace, and but shap'd

hy fire. This mighty quoit Action wont to rear, And from his whirling arm dismiss in air: The giant by Achilles slain, he stow'd Among his spoils this memorable load. For this he bids those nervous artists vie, That teach the disc to sound along the

sky." Book xxiii. 975.

« AnteriorContinuar »